1. Field of the Invention
The present invention relates to a system for analyzing the intensity distribution across an ultraviolet (UV) laser beam. The various commercial and medical applications of laser beams makes it necessary to monitor and control the intensity distribution across the face of the beam and various techniques have been devised for measuring the intensity profile of laser radiation.
One such technique is disclosed in the above cited patent application in which a beam intensity profilometer produces fluorescent emission distribution having a spacial distribution linearly proportional to the local intensity of the incident UV beam impinging upon the profilometer. The spacial distribution of the UV beam is analyzed as a function of the fluorescent emission.
The present invention makes use of the fluorescent materials disclosed in the above cited application which provide a visible fluorescent emission as a function of the impinging UV beam to be analyzed. However, the present invention analyzes a line or linear section across the face of the impinging UV laser beam.
2. Description of the Prior Art
A number of prior patents exist directed to the measuring of the wave front of a laser beam and these include: U.S. Pat. Nos. 3,462,601; 3,549,886; 3,598,998; 3,680,965; 4,260,251; 4,376,892; 4,490,039; 4,602,272; and 4,670,646. However, none of these patents disclose the use of a strip of UV activated fluorescent material as with the present invention.
A description of various prior art systems was disclosed in a paper entitled "Characterization of UV Laser Beams Using Fluorescence", by Telfair et al., delivered at the Society of Photo-Optical Instrumentation Engineers (SPIE) on Jan. 15, 1988 in Los Angeles, Calif. and in articles entitled "Choosing And Using Laser-Beam-Profile Monitors", by Edwards, in Laser Focus/Electron-Optics, May 1987, pgs. 76-84 and "Laser Beam Profiling The Automated Way", by Rypma, Photonics Spectra, August 1987, pgs. 67-74.
A material which has been found to be particularly useful in converting invisible UV radiation to visible fluorescent radiation is a rare earth doped garnet, Ce 3+: Y3 A15 O12 (YAG). The ability of this material to fluoresce is described in an article entitled "CATHODOLUMINESCENT GARNET LAYERS" by J. M. Robertson, Thin Solid Films, 114 (1984) 221-240. The article, however, does not disclose the concept of measuring a high powered UV laser beam with an instrument incorporating the doped YAG material.
The above patents and additional publications are described and discussed in the above-cited parent application. None of this prior art discloses the present system of utilizing UV activated fluorescent material to analyze a section of a UV beam.